Drive mechanism for a medication delivery device and medication delivery device

ABSTRACT

A drive mechanism for a medication delivery device is presented having a housing, a rotation member that rotates in a first direction with respect to the housing during setting of a dose of a medication and rotates in a second direction with respect to the housing during delivery of the dose, the second direction being opposite to the first direction. The device also has a piston rod that is displaced in a distal direction with respect to the housing for delivering the dose, a drive member which follows rotational movement of the rotation member in the second direction during delivery of the dose, and a stop member which prevents rotational movement of the drive member with respect to the housing in the first direction during setting of the dose.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/667,687, filed Aug. 3, 2017, which is a continuation of U.S.patent application Ser. No. 14/459,440, filed Aug. 14, 2014, now U.S.Pat. No. 9,750,888, which is a continuation of U.S. patent applicationSer. No. 12/333,459, filed Dec. 12, 2008, now U.S. Pat. No. 8,840,591.The entire disclosure contents of these applications are herewithincorporated by reference into the present application.

FIELD OF THE INVENTION

The present invention relates to a drive mechanism for a medicationdelivery device and a medication delivery device incorporating such adrive mechanism.

BACKGROUND

In a medication delivery device, a piston within a cartridge thatcontains medication may be displaced with respect to the cartridge inthe distal direction by a piston rod which moves in the distal directionwith respect to the cartridge. Thereby, a dose of medication can beexpelled from the cartridge. A medication delivery device is describedin US 2007/0123829 A1, for example.

It is often desirable that the actually delivered dose of medicationmatches the dose which was previously set for injection by a user orwhich the device was designed to deliver as close as possible, i.e. doseaccuracy should be good.

It is an object to provide for a drive mechanism that facilitatesprovision of an improved medication delivery device, for example adevice with good dose accuracy. Furthermore, an improved medicationdelivery device should be provided for.

This object may be achieved by a drive mechanism according to theindependent claim. Further features, advantages and expediencies aresubject matter of the dependent claims.

SUMMARY

According to one aspect, a drive mechanism for a medication deliverydevice comprises a housing having a proximal end and a distal end, arotation member which is adapted to be rotated in a first direction withrespect to the housing during setting of a dose of a medication and tobe rotated in a second direction with respect to the housing duringdelivery of the dose, the second direction being opposite to the firstdirection. Furthermore, the drive mechanism comprises a piston rod whichis adapted to be displaced in a distal direction with respect to thehousing for delivering the dose, a drive member which follows rotationalmovement of the rotation member in the second direction during deliveryof the dose, and a stop member which prevents rotational movement of thedrive member with respect to the housing in the first direction duringsetting of the dose, wherein the rotational movement of the drive memberin the second direction is converted into movement of the piston rod inthe distal direction with respect to the housing.

Mechanical interaction of stop member and drive member, for example,interlocking, engagement and/or abutment, during rotation of therotation member in the first direction may prevent rotational movementof the drive member with respect to the housing in the first directionand, in particular, with respect to the stop member during setting ofthe dose. Thus, rotation of the drive member during dose setting can beavoided. The drive member may be coupled to the piston rod so as toconvert its rotational movement in the second direction into distalmovement of the piston rod with respect to the housing. The drive membermay (also) be coupled to the piston rod so as to convert its rotationalmovement in the first direction with respect to the housing intoproximal movement of the piston rod with respect to the housing.Accordingly, the risk of the piston rod being moved in the proximaldirection during dose setting can be reduced by preventing rotationalmovement of the drive member in the first direction during setting ofthe dose due to provision of the stop member. Unintentional proximalmovement of the piston rod may result in decreased dose accuracy.Consequently, dose accuracy may be improved by preventing (any) rotationof the drive member with respect to the housing during dose setting.

According to a preferred embodiment, the drive member and the rotationmember are rotatable around a common rotation axis.

According to another preferred embodiment, the piston rod is displacedin the distal direction with respect to the housing along the rotationaxis. The rotation axis may run along the piston rod and, in particular,along a main direction of extent of the piston rod.

According to another preferred embodiment, the piston rod is displacedin the distal direction with respect to the housing transversally withrespect to the rotation axis. The rotation axis may, in particular, runtransversally, for example perpendicularly, with respect to adisplacement axis along which the piston rod is displaced in the distaldirection with respect to the housing and, in particular, with respectto the drive member. The displacement axis may run along the piston rodand, in particular, along a main direction of extent of the piston rod.

According to another preferred embodiment, the drive mechanism comprisesa dose member. The dose member is preferably movable with respect to thehousing during setting and/or delivery of the dose. The dose member maybe movable in the proximal direction with respect to the housing forsetting the dose. The dose member may be movable in the distal directionwith respect to the housing for delivering the set dose. Movement of thedose member with respect to the housing may be converted into rotationalmovement of the rotation member with respect to the housing. Movement ofthe dose member for setting the dose may be converted into rotationalmovement of the rotation member with respect to the housing in the firstdirection. Movement of the dose member for delivering the set dose maybe converted into rotational movement of the rotation member withrespect to the housing in the second direction. The dose member may besecured against rotational movement with respect to the housing. Thedose member may be splined to the housing, for example. The dose membermay be movable with respect to the rotation member. Movement of the dosemember with respect to the rotation member may be converted intorotational movement of the rotation member.

According to another preferred embodiment, the dose member and therotation member are engaged, preferably threadedly engaged and/orpermanently engaged. Rotational movement of the rotation member may beachieved by the (threaded) engagement which may convert (linear)movement of the dose member into rotational movement of the rotationmember with respect to the housing.

According to another preferred embodiment, the dose member and therotation member are coupled to one another via or (immediately) by alever. The lever may be pivotally around the rotation axis duringmovement of the dose member for setting and/or delivery of the dose. Thelever may be pivotally around the rotation axis in the first directionduring movement of the dose member for setting of the dose. The levermay be pivotally around the rotation axis in the second direction duringmovement of the dose member for delivering the dose.

According to another preferred embodiment, the drive member, preferablypermanently, abuts and/or engages one of or both of stop member androtation member during (rotational) movement of the rotation member forsetting and delivery of the dose. The drive member may be coupled tostop member and/or rotation member during setting and delivery of thedose.

According to another preferred embodiment, the drive member is arrangedbetween stop member and rotation member.

According to another preferred embodiment, the rotation member and thedrive member and/or the stop member and the drive member are held inabutment by a force provided by a resilient member, in particular aspring member, during setting and delivery of the dose, in particularduring rotational movement of the rotation member in the first directionand in the second direction. Preferably, the rotation member and thestop member are held in abutment with the drive member by the forceprovided by the spring member during setting and delivery of the dose.

According to another preferred embodiment, the drive member and therotation member are coupled, preferably permanently, to one another by a(first) uni-directional friction clutch mechanism. This friction clutchmechanism may be configured to permit relative rotational movementbetween rotation member and drive member during movement of the rotationmember for setting of the dose and to prevent relative rotationalmovement of rotation member and drive member during movement of therotation member for delivery of the dose.

According to another preferred embodiment, the drive member and the stopmember are coupled, preferably permanently, to one another by a (second)uni-directional friction clutch mechanism. This friction clutchmechanism may be configured to prevent relative rotational movementbetween stop member and drive member during movement of the rotationmember for setting of the dose and to permit relative rotationalmovement of stop member and drive member during movement of the rotationmember for delivery of the dose.

According to another preferred embodiment, the stop member is securedagainst rotational movement with respect to the housing.

According to another preferred embodiment, the stop member is (linearly)displaceable with respect to the housing, preferably without rotating.The stop member may be displaceable along the rotation axis with respectto the housing. The rotation member may be secured against displacementwith respect to the housing. Alternatively, the rotation member isdisplaceable with respect to the housing. Rotation member and stopmember may be displaceable with respect to the housing.

Alternatively, the stop member may be secured against rotation anddisplacement with respect to the housing. The rotation member may bedisplaceable with respect to the housing, in this case.

According to another preferred embodiment, the spring member abuts thestop member or is integrated in the stop member.

According to another preferred embodiment, the drive member, the stopmember, the rotation member and/or the dose member may be formed as ormay comprise a sleeve. A rod, for example the piston rod or an axis rodwhich defines the rotation axis may extend through one of, more of orall of drive sleeve, stop sleeve, rotation sleeve and dose sleeve.

According to another preferred embodiment, the drive member engages thepiston rod.

According to another preferred embodiment, the drive member is splinedto the piston rod.

According to another preferred embodiment, the rotational movement ofthe drive member in the second direction is converted into rotationalmovement of the piston rod with respect to the housing, in particularrotational movement in the same direction and/or by the same angle, andmovement of the piston rod with respect to the housing in the distaldirection. The piston rod may be threadedly coupled to the housing, inparticular threadedly engaged with the housing, for this purpose.

According to another preferred embodiment, the rotational movement ofthe drive member is converted into pure linear movement of the pistonrod in the distal direction, Accordingly, the piston rod may be moved inthe distal direction without rotating with respect to the housing. It isparticularly suitable for the drive member to comprise (radial) gearteeth for engaging the piston rod, for this purpose.

Another aspect relates to a medication delivery device that comprises adrive mechanism as described above. The device furthermore comprises acartridge that comprises a plurality of doses of a medication. A pistonmay be arranged within the cartridge, the piston being displaceable inthe distal direction with respect to the cartridge for delivering a doseof medication from the cartridge. The piston rod may be arranged todrive the piston in the distal direction with respect to the cartridge.The cartridge may be attached, permanently or releasably, to thehousing.

Features which are described herein above and below in connection withthe drive mechanism may also be applied for the corresponding medicationdelivery device and vice versa.

Further features, refinements and expediencies become apparent from thefollowing description of the exemplary embodiments in connection withthe figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 schematically shows a partly sectional side view of an exemplaryembodiment of a medication delivery device.

FIG. 2 schematically shows a perspective sectional view of a part of adrive mechanism according to a first embodiment with schematicallyindicated movements of elements thereof during setting of a dose.

FIG. 3 schematically shows a more detailed side view of a part of FIG.2.

FIG. 4 schematically shows a perspective sectional view of a part of thedrive mechanism according to the first embodiment with indicatedmovements of elements thereof during delivery of a dose.

FIG. 5 schematically shows a more detailed side view of a part of FIG.4.

FIG. 6 schematically shows a perspective sectional view of a part of adrive mechanism that is configured in accordance with the firstembodiment.

FIG. 7 schematically shows a perspective view of a part of the drivemechanism of FIG. 2 with indicated movements of elements thereof duringdelivery of a dose.

FIG. 8 schematically shows a perspective view of a part of a drivemechanism that is configured in accordance with the first embodiment.

FIG. 9 schematically shows a perspective view of a part of a drivemechanism that is configured in accordance with the first embodiment.

FIG. 10 schematically shows an oblique sectional view of a drivemechanism according to a second embodiment.

FIG. 11 schematically shows an oblique sectional view of a drivemechanism according to a third embodiment.

FIG. 12 schematically shows an oblique sectional view of a part of thedrive mechanism of FIG. 11.

FIG. 13 schematically shows an oblique sectional view of a part of thedrive mechanism of FIG. 11.

FIG. 14 schematically shows an oblique sectional view of a part of thedrive mechanism of FIG. 11.

FIG. 15 schematically shows an oblique sectional view of a part of thedrive mechanism of FIG. 11.

FIG. 16 shows a schematic sectional view of a part of a resettable drivemechanism according to an embodiment in delivery position.

FIG. 17 shows the resettable drive mechanism of FIG. 16 in resetposition.

Like elements, elements of the same kind and identically acting elementsare provided with the same reference numerals in the figures.

DETAILED DESCRIPTION

Turning now to FIG. 1, a medication delivery device 1 comprises acartridge unit 2 and a drive unit 3. The cartridge unit 2 comprises acartridge 4. Medication 5 is retained in the cartridge 4. The medication5 is preferably liquid medication. The cartridge 4 preferably comprisesa plurality of doses of the medication 5. The medication 5 may compriseinsulin, heparin, or growth hormones, for example. The cartridge 4 hasan outlet 6 at its distal end. Medication 5 can be dispensed from thecartridge through outlet 6. The device 1 may be a pen-type device, inparticular a pen-type injector. The device 1 may be a disposable or areusable device. The device 1 may be a device configured to dispensefixed doses of the medication or variable, preferably user-settable,doses. The device 1 may be a needle-based or a needle free device. Thedevice 1 may be an injection device.

The term “distal end” of the medication delivery device 1 or a componentthereof may refer to that end of the device or the component which isclosest to the dispensing end of the device 1. The term “proximal end”of the medication delivery device 1 or a component thereof may refer tothat end of the device or the component which is furthest away from thedispensing end of the device, In FIG. 1, the distal end of the device 1was assigned reference numeral 7 and the proximal end of the device wasassigned reference numeral 8.

The outlet 6 may be covered by a membrane 9, which protects medication 5against external influences during storage of the cartridge. Formedication delivery, membrane 9 may be opened, e.g. pierced. Forexample, membrane 9 may be pierced by a needle unit (not explicitlyshown). The needle unit may be (releasably) attached to the distal endof the cartridge unit 2. The needle unit may provide for fluidcommunication from the inside of the cartridge 4 to the outside of thecartridge through outlet 6.

A piston 10 is retained within the cartridge 4. The piston 10 is movablewith respect to the cartridge. The piston 10 may seal the medication 5within the cartridge. The piston 10 expediently seals the interior ofthe cartridge 4 proximally. Movement of the piston 10 with respect tothe cartridge 4 in the distal direction causes medication 5 to bedispensed from the cartridge through outlet 6 during operation of thedevice.

The cartridge unit 2 furthermore comprises a cartridge retaining member11, The cartridge 4 is retained within the cartridge retaining member11. The cartridge retaining member 11 may stabilize the cartridge 4mechanically. Additionally or alternatively, the cartridge retainingmember 11 may be provided with a fixing member (not explicitly shown)for attaching the cartridge unit 2 to the drive unit 3.

The cartridge unit 2 and the drive unit 3 are secured to one another,preferably releasably secured. A cartridge unit 2 which is releasablysecured to the drive unit may be detached from the drive unit 3, forexample in order to allow for providing for a new cartridge 4, if all ofthe doses of medication which once were in the cartridge formerlyattached to the drive unit 3 have already been dispensed. The cartridgeretaining member 11 may be releasably secured to the drive unit 3 via athread, for example.

Alternatively, the cartridge retaining member 11 may be dispensed with.It is particularly expedient, in this case, to apply a robust cartridge4 and to attach the cartridge directly to the drive unit 3.

The drive unit 3 is configured for transferring force, preferablyuser-exerted force, particularly preferably manually exerted force, tothe piston 10 for displacing the piston 10 with respect to the cartridge4 in the distal direction. A dose of medication may be dispensed fromthe cartridge in this way. The size of the delivered dose may bedetermined by the distance by which the piston 10 is displaced withrespect to the cartridge 4 in the distal direction.

The drive unit 3 comprises a drive mechanism. The drive mechanismcomprises a piston rod 12. The piston rod 12 may be configured fortransferring force to the piston 10, thereby displacing the piston inthe distal direction with respect to the cartridge 4. A distal end faceof the piston rod 12 may be arranged to abut a proximal end face of thepiston 10. A bearing member (not explicitly shown) may be arranged toadvance the piston 10, preferably to abut the proximal end face of thepiston 10. The bearing member may be arranged between piston 10 andpiston rod 12. The bearing member may be fixed to the piston rod 12 or aseparate member. If the piston rod 12 is configured to be rotated duringoperation of the device, for example during dose delivery, it isparticularly expedient to provide for a bearing member. The bearingmember may be displaced together with the (rotating) piston rod withrespect to the housing. The piston rod may be rotatable with respect tothe bearing member. In this way, the risk that the rotating piston roddrills into the piston and thereby damages the piston is reduced.Accordingly, while the piston rotates and is displaced with respect tothe housing, the bearing member is preferably only displaced, i.e. doesnot rotate. The piston rod may be bounded by the bearing member.

The drive unit 3 comprises a housing 13 which may be part of the drivemechanism. The piston rod 12 may be retained in the housing. A proximalend side 14 of the cartridge unit 2 may be secured to the drive unit 3at a distal end side 15 of the housing 13, for example via a threadedconnection. Housing 13, cartridge 4 and/or cartridge retaining member 11may have a tubular shape.

The term “housing” shall preferably mean any exterior housing (“mainhousing”, “body”, “shell”) or interior housing (“insert”, “inner body”)which may have a unidirectional axial coupling to prevent proximalmovement of specific components. The housing may be designed to enablethe safe, correct, and comfortable handling of the medication deliverydevice or any of its mechanism. Usually, it is designed to house, fix,protect, guide, and/or engage with any of the inner components of themedication delivery device (e.g., the drive mechanism, cartridge,piston, piston rod), preferably by limiting the exposure tocontaminants, such as liquid, dust, dirt etc. In general, the housingmay be unitary or a multipart component of tubular or non-tubular shape.

The term “piston rod” shall preferably mean a component adapted tooperate through/within the housing, which may be designed to transferaxial movement through/within the medication delivery device, preferablyfrom the drive member to the piston, for example for the purpose ofdischarging/dispensing, an injectable product. Said piston rod may beflexible or not. It may be a simple rod, a lead-screw, a rack and pinionsystem, a worm gear system, or the like. “piston rod” shall further meana component having a circular or non-circular cross-section. It may bemade of any suitable material known by a person skilled in the art andmay be of unitary or multipart construction.

The drive unit 3 comprises a dose part 16. The dose part 16 is movablewith respect to the housing 13. The dose part 16 may be movable in theproximal direction with respect to the housing for setting of a dose ofthe medication 5 which is to be delivered and in the distal directionwith respect to the housing for delivery of the set dose. The dose part16 is preferably connected to the housing 13. The dose part 16 may besecured against rotational movement with respect to the housing. Thedose part 16 may be moved (displaced) between a proximal end positionand a distal end position with respect to the housing 13 (not explicitlyshown). The distance by which the dose part is displaced with respect tothe housing during setting of the dose may determine a size of the dose.The proximal end position and the distal end position may be determinedby a respective stop feature which may limit the proximal or distaltravel of the dose member with respect to the housing. The device 1 maybe a variable dose device, i.e. a device configured for delivering dosesof medication of different, preferably user-settable, sizes.Alternatively, the device may be a fixed dose device.

The device 1 may be a manually, in particular non-electrically, drivendevice. The (user-applied) force which causes the dose part 16 to bemoved with respect to the housing 13 in the distal direction may betransferred to the piston rod 12 by the drive mechanism. For thispurpose, other elements of the drive mechanism may be provided which arenot explicitly shown in FIG. 1. The drive mechanism is preferablyconfigured to not move the piston rod 12 with respect to the housing 13when the dose part is moved in the proximal direction with respect tothe housing for setting of the dose.

Embodiments of a drive mechanism which are suitable to be provided inthe medication delivery device 1 as it was described above are describedin more detail below.

A first embodiment of a drive mechanism which is suitable for beingimplemented in the medication delivery device 1 as described above isdescribed in connection with FIGS. 2 to 9.

The drive mechanism comprises a housing part 17. The housing part 17 hasa proximal end 18 and a distal end 19. The housing part 17 may be(outer) housing 13 of FIG. 1, a part thereof or an insert within housing13, which insert is preferably secured against rotational and axialmovement with respect to housing 13. The housing part 17 may be aninsert sleeve, for example. The insert sleeve may be snap-fitted orglued to housing 13, for example. The housing part 17 may have a tubularshape. Housing part 17 may comprise outer fixing elements 64, forexample snap-fit elements, for fixing housing part 17 to housing 13 (cf.FIG. 8).

The piston rod 12 is retained in the housing 13, preferably withinhousing part 17. The piston rod 12 is driven in the distal directionwith respect to the housing part 17 during dose delivery.

The drive mechanism furthermore comprises a drive member 20. Drivemember 20 is retained within the housing part 17. Drive member 20 isconfigured to transfer force, preferably torque, to the piston rod 12.The transferred force may cause the piston rod 12 to be displaced in thedistal direction with respect to the housing part 17 for dose delivery.

Drive member 20 is rotatable with respect to housing part 17. The drivemember 20 may engage the piston rod 12. Rotational movement of the drivemember, for example rotational movement in a second direction may beconverted into distal movement of the piston rod 12 with respect to thehousing part 17. This is explained in more detail below.

The drive mechanism furthermore comprises a rotation member 21. Therotation member 21 is rotatable with respect to the housing part 17 in afirst direction, in particular for setting of a dose of the medication,and in a second direction, in particular for delivering the set dose.The second direction is opposite to the first direction. The firstdirection may be counter-clockwise and the second direction may beclockwise as seen from the proximal end of the device, for example.

Drive member, rotation member and/or piston rod are preferablyconfigured to be rotatable about a (common) rotation axis. The rotationaxis may extend through drive member, rotation member and/or piston rod.The rotation axis may be the main longitudinal axis of the piston rod.The rotation axis may run between the proximal end and the distal end ofthe housing part 17.

The rotation member 21 is coupled to the drive member 20 by anuni-directional clutch mechanism, in particular a friction clutchmechanism. This clutch mechanism permits rotational movement of therotation member 21 with respect to the drive member 20 when the rotationmember rotates in the first direction with respect to the housing part17. The clutch mechanism prevents rotational movement of the rotationmember 21 with respect to the drive member 20, when the rotation memberrotates in the second direction with respect to the housing part 17. Thedrive member 20 may thus follow rotational movement of the rotationmember 21 in the second direction with respect to the housing part 17.

The drive member 20 is arranged to abut and/or engage the rotationmember and, in particular, engages rotation member 21. The drive member20 comprises a toothing 22 at one end, e.g. its proximal end. Therotation member comprises a toothing 23 at one end which end faces thedrive member 20, e.g. its distal end. Toothing 22 comprises a pluralityof teeth 24. Toothing 23 comprises a plurality of teeth 25. Teeth 24and/or 25 may extend along the rotation axis. Toothings 22 and 23 may beconfigured to mate with one another.

A respective tooth of teeth 24 and/or teeth 25 may be ramp-shaped, inparticular along the azimuthal (angular) direction as seen from therotation axis. The ramp of the respective tooth is limited (in theangular direction) by a steep end face of that tooth, i.e. a face of thetooth that runs parallel to the rotation axis or includes a smallerangle with the rotation axis when projected on this axis than the rampwhen projected on this axis. The steep end face is followed by the rampof the next tooth.

The teeth 24 may be disposed along the perimeter of that end of thedrive member 20 which faces the rotation member 21. The teeth 25 may bedisposed along the perimeter of the rotation member 21 at that end whichfaces the drive member 20.

When the steep end faces of two teeth abut and the rotation member isrotated further on in the second direction, the steep sides stay inabutment and drive member 20 follows the rotation of rotation member 21.When the rotation member rotates in the first direction, the ramp of theteeth—which ramps, in particular, run obliquely with respect to therotation axis—slide along each other and, in consequence, the rotationmember 21 may rotate with respect to the drive member 20.

The drive mechanism furthermore comprises a stop member 26. The drivemember may be arranged between the stop member 26 and the rotationmember 21. The stop member 26 is configured for preventing rotationalmovement of the drive member 20 in the first direction with respect tothe housing part 17 during setting of a dose, i.e. when the rotationmember rotates in the first direction. Thus, the rotation member 21 mayrotate in the first direction with respect to the housing part 17,whereas the drive member 20 and the stop member 21 don't rotate.

The stop member 26 is coupled to the drive member 20 by anotheruni-directional clutch mechanism, in particular a friction clutchmechanism. This clutch mechanism prevents rotational movement of thedrive member 20 with respect to the stop member 20 when the rotationmember rotates in the first direction with respect to the housing part17. The clutch mechanism permits rotational movement of the drive member20 with respect to the stop member 26, when the rotation member rotatesin the second direction with respect to the housing part 17.

Thus, the rotation member 21 may rotate with respect to the drive member20 and the stop member 26 in the first direction during setting of thedose, with rotation of the drive member being prevented by itsinteraction with the stop member, and rotation member as well as drivemember may rotate with respect to the stop member in the seconddirection during delivery of the dose.

The stop member may be arranged to abut and/or engage the drive memberduring setting of the dose and, preferably, during delivery of the dose.The stop member 26 has a toothing 27 at one end which faces the drivemember, e.g. its proximal end. The teeth may be ramp-shaped. with asteep side and a less steep ramp. The teeth may be disposed azimuthallyalong the perimeter of the stop member.

Drive member 20 has a toothing 28 at one end which faces the stopmember, e.g. its distal end. Toothings 22 and 28 of the drive member 20are oppositely disposed. Toothing 28 may be configured in accordancewith toothing 21 of the rotation member. Toothing 22 may be configuredin accordance with toothing 27 of the stop member. Toothings 27 and 28,in particular the steep sides of the teeth, do cooperate, e.g. abut, forpreventing rotation of the drive member 20 with respect to the housingpart 17 and, in particular, with respect to the stop member 26 in thefirst direction.

Stop member 26 is preferably secured against rotational movement withrespect to the housing part 17. Stop member 26 may be fixed to thehousing or integrated into the housing. Stop member 26 may be fixedagainst displacement with respect to the housing part 17 or displacementwith respect to the housing part 17 may be allowed.

As it is illustrated in the present embodiment, stop member 26 isdisplaceable with respect to the housing but non-rotatable with respectto the housing part 17. For that purpose, one or a plurality of,preferably oppositely disposed, guide features, for example guide lugs29, are provided in the stop member 26. The respective guide feature 29engages a corresponding guide slot 30 which may be provided in thehousing, e.g. in housing part 17. This can be seen in FIGS. 2 to 5. Aguide feature 29 cooperates with a guide slot 30 to prevent rotationalmovement of the stop member with respect to the housing part 17, withaxial movement of the stop member 26 with respect to the housing beingallowed. The axial movement of the stop member 26 may compensate forplay between components of the drive mechanism during operation.

From the group comprising drive member 20, stop member 26 and rotationmember 21 one or more members, preferably two members or three members,may be axially displaceable with respect to the housing part 17 and,preferably, with respect to the piston rod 12. Therein, the drive memberand another one of the recited members may be axially displaceable withrespect to the housing. The remaining member may be secured againstaxial displacement or may also be axially displaceable during operationof the drive mechanism for medication delivery. Accordingly, if thedrive member and the stop member are axially displaceable, the rotationmember may be axially secured or axially displaceable and so on. Playbetween the components caused by relative (axial) movement of componentsof the clutch mechanism with respect to the housing can be compensatedfor in this way. The distance by which the respective components may beaxially displaced with respect to the housing may correspond to the(maximum) depth of a tooth of the respective toothing 22 or 28 of thedrive member. Alternatively, the distance may be greater than the(maximum) depth of a tooth of the respective toothing.

Furthermore, the drive mechanism comprises a resilient member 31,preferably a spring member. The resilient member 31 may be biased duringmedication delivery operation of the drive mechanism. The resilientmember may provide for a force that tends to keep the drive member 20 inengagement with the stop member 26 and/or the rotation member 21. Theforce may be exerted along the rotation axis. In the situation shown inFIGS. 2 to 5, this force may be exerted in the proximal direction. Theresilient member 31 may be a helical (coil) spring. The resilient member31 may be a compression spring.

The resilient member 31 may keep the drive member 20 and the stop member26 in (permanent) mechanical contact, e.g. in abutment, with each otherduring setting and delivery of a dose of the medication. Alternativelyor additionally, the resilient member 31 may keep the drive member 20and the rotation member 26 in (permanent) mechanical contact, preferablyabutment, with each other during setting and delivery of a dose of themedication.

The resilient member 31 may be integrated within stop member 26 or aseparate component. The resilient member 31 may be arranged on thedistal end side of the stop member 26.

The drive mechanism furthermore comprises a support member 32. Supportmember 32 is expediently fixed against axial and rotational movementwith respect to the housing part 17 or integrated into housing part 17.Support member 32 is arranged on that side of the drive member 20 whichis remote from the stop member 26. Support member 32 may be aprotrusion, for example a ring-like protrusion. Rotation member 21 mayextend through an opening in support member 32. The support member 32may provide for a counter force to the force which is exerted by theresilient member 31. Permanent abutment of the rotation member with thedrive member and of the drive member with the stop member during settingand delivery of medication is facilitated in this way.

The rotation member 21 has an (radially) outwardly protruding member 33,for example a flange portion. The protruding member 33 is expedientlyprovided for abutting support member 32, in particular the distal endside of support member 32.

Another support 48 (cf. FIG. 6) may be provided for providing acounterforce to the force exerted by the resilient member 31. Support 48is arranged on that side of the drive member 20 which is remote from therotation member 21. Support 48 is arranged on that side of the stopmember 26 which is remote from the support member 32. The support 48 maybe arranged to abut the resilient member 31. The support 48 may besecured against axial and rotational movement with respect to thehousing part 17, with respect to the housing 13 or integrated into thehousing 13, for example into (additional) housing part 40 (cf. FIG. 6).

The drive mechanism furthermore comprises a dose member 34. Dose member34 may be dose part 16 or may be a part of the dose part 16 of FIG. 1.Dose member 34 is movable with respect to the housing in the proximaldirection for setting of a dose and for delivery of the dose. Forexample, the dose member 34 may be moved in the proximal direction withrespect to the housing part 17 during dose setting and in the distaldirection with respect to the housing part 17 during dose delivery. Thedose member 34 may engage the housing part 17 or, alternatively, anotherpart of housing 13 (not explicitly shown). Dose member 34 is preferablysecured against rotational movement with respect to the housing part 17.The dose member 34 may comprise a guide feature 35, for example a guidelug or a guide slot, that engages another guide feature, for example aguide slot or a guide lug, respectively, that is provided in the housingpart 17 or the housing 13.

Dose member 34 may be moved in the proximal direction and in the distaldirection with respect to rotation member 21. Dose member 34 is arrangedto be couplable and is preferably (permanently) coupled to rotationmember 21 such that movement of the dose member, e.g. in the proximaldirection with respect to the housing part 17, for setting a dose of themedication is converted into rotational movement of the rotation memberin the first direction and movement of the dose member, e.g. in theproximal direction with respect to the housing part 17, for deliveringthe dose is converted into rotational movement of the rotation member 21in the second direction opposite to the first direction.

The rotation member 21 may be provided with an (outer) thread 36. Thread36 may be engaged with one of or a plurality of engagement members 42 ofdose member 34. The respective engagement member may be arranged on theinside of the dose member. The respective engagement member may be athread or a part of a thread, for example. Thus, dose member 34 androtation member 21 may be threadedly coupled, in particularly threadedlyengaged. The rotation member 21 may be arranged inside the dose member21.

The rotation member 21, the drive member 20, the stop member 26 and/orthe dose member 34 may be or may comprise a respective sleeve. Thepiston rod 12 may be arranged to be driven and, in particular, may bedriven through one of, more of or all of those sleeves. The piston rod12 may run through one of, more of or all of those sleeves.

The drive member 20 and the piston rod 12 are configured for rotationalmovement of the drive member 20 with respect to the housing beingconverted into rotational movement of the piston rod with respect to thehousing. The drive member 20 may engage the piston rod 12. The pistonrod 12 is displaceable with respect to the drive member 20 along adisplacement axis. Presently, the displacement axis runs along therotation axis. The drive member 20 may be splined to the piston rod 12,for example.

The piston rod 12 is threadedly coupled to the housing 13. The pistonrod 12 may be provided with an outer thread 49, for example. The pistonrod 12 may extend through and be engaged with a (part) thread in opening39 which is provided in housing part 40, for example in support 48 (cf.FIG. 6). Housing part 40 may be formed integrally with housing part 17,may be a housing part fixed thereto or may be a housing part securedseparately from housing part 17 to housing 13.

The piston rod 12 comprises an engagement track 37, preferably twooppositely disposed engagement tracks, on the outside. The (respective)engagement track 37 may interrupt thread 49. The (respective) engagementtrack 37 preferably extends along the axia along which the piston rod isdisplaceable with respect to the housing and, in particular, withrespect to the drive member.

Rotational movement of the drive member 20 with respect to the housingmay thus be converted into rotational movement of the piston rod 12 withrespect to the housing and the rotational movement of the piston rod 12is, on account of the threaded engagement of the piston rod and thehousing (part), converted into movement of the piston rod with respectto the housing in the distal direction.

The dose part 16 (cf. FIG. 1) may comprise a dose knob 41 (cf. FIG. 8).Dose knob 41 may be configured to be gripped by a user. Dose knob 41 maybe arranged and connected to the dose member 34 at the proximal end.Dose knob and dose member may be unitary.

In the following, operation of the present drive mechanism fordelivering medication from the cartridge 4 of FIG. 1 is described.

To set a dose, a user may manually move dose member 34 in the proximaldirection (arrow 43) with respect to the housing part 17 (cf. FIGS. 2,3, 8 and 9). To do so, the user may grip dose knob 41 and pull it in theproximal direction. Dose member 34 moves proximally also with respect tothe rotation member 21. Proximal movement of the rotation member isprevented. by support member 32 which abuts protruding member 33 ofrotation member 21. Consequently, the proximal movement of dose member34 with respect to the housing part 17 is converted into rotationalmovement of the rotation member 21 in the first direction (arrow 44)with respect to the housing part 17, in particular on account of thethreaded engagement of dose member 34 and rotation member 21. Thus, therotation member 21 rotates in the first direction—counter-clockwise asseen from the proximal end of the rotation member—with respect to thehousing. Rotation member 21 also rotates with respect to the drivemember 20 and to the stop member 26. The drive member 20 is preventedfrom rotating in the first direction by interaction with the stop member26, e.g. by interlocking of toothings 27 and 28. As the piston rod 12 iscoupled to the drive member 20 and rotation in the first direction ofthe drive member would cause the piston rod to travel in the proximaldirection, the piston rod 12 is prevented from being driven in theproximal direction by interaction of stop member 26 and drive member 20.Dose accuracy can be increased in this way.

When the rotation member 21 rotates in the first direction, the ramps ofthe teeth of toothing 23 of rotation member 21 slide along the ramps ofthe teeth of toothing 22. Thus, a tooth of the rotation member may indexaround the rotation axis until the tooth engages one of the next teethof toothing 22 of drive member 20. The teeth of rotation member 21 slidealong the ramps of the teeth of drive member 20. During this movement,drive member 20 and, in particular, stop member 26 are displaced alongthe rotation axis with respect to piston rod 12 and housing by adistance determined by, preferably equal to, the depth of a tooth oftoothing 22, before a tooth of toothing 23 (totally) disengages thattooth of toothing 22. Afterwards, the tooth of the rotation member 21engages the next tooth of toothing 22 and the force provided byresilient member 31 moves drive member 20 and, in particular, stopmember 26 back along the rotation axis into the axial start position. Anaccording movement of stop member and drive member in the distaldirection and back into the proximal direction is indicated by doublearrow 45 in FIGS. 2 and 3.

A tooth of the rotation member which engages the next tooth of the drivemember may cause an audible and/or tactile feedback to the user.

The drive mechanism is suitable for a fixed dose device or a usersettable dose device. The size of the fixed dose of medication which isto delivered or the increments in which a user-settable dose may bevaried by a user are preferably determined by the distribution of theteeth of the respective toothings in the drive member, rotation memberand stop member. The rotation member may be rotated over more than oneteeth (dose increment) of the drive member for a user-settable dosedevice and over one teeth (only) for a fixed dose device. The number ofteeth in the drive member 20 over which the rotation member 21 rotatesduring dose setting determines the size of the dose which is actuallydelivered. The dose member and the rotation member may be adapted to oneanother such that the rotation member may rotate only by one tooth for afixed dose device and by more than one tooth for a variable dose device.

After the dose has been set, the dose part 16 and with it the dosemember 34 is moved (pushed) by the user in the distal direction withrespect to housing part 17 (arrow 46; cf. FIGS. 4, 5, 8 and 9). Thus,the dose member 34 is moved in the distal direction with respect to thehousing part 17. The rotation member 21 accordingly rotates in thesecond direction, which is opposite to the first direction, with respectto the housing (arrow 47, cf. FIGS. 4 to 9). Drive member 20 followsrotational movement of the rotation member in the second direction.Rotational movement of the drive member 20 in the second direction isconverted into rotational movement of the piston rod 12 in the seconddirection, which movement, in turn, is converted into movement of thepiston rod 12 in the distal direction. Accordingly, the piston 10 ofFIG. 1 may be displaced in the distal direction with respect to thecartridge 4 and a dose of medication 5 is dispensed from the cartridgethe amount of which corresponds to the previously set dose.

During dose delivery, toothings 22 and 23 interlock and ramps of theteeth of toothing 28 of the drive member 20 slide along ramps of theteeth of toothing 27 of stop member 26. This movement is similarly asdescribed above for the relative rotational movement of rotation memberand drive member with opposite rotation direction. The stop member 26 isthereby displaced in the distal direction with respect to the drivemember 20 by a distance corresponding to the depth of a tooth oftoothing 27 in stop member 26. Resilient member 28 forces the stopmember 26 back into the axial starting position, when the next tooth oftoothing 28 is engaged by the respective tooth of toothing 27 (doublearrow 65).

A tooth of the drive member which engages the next tooth of the stopmember may cause an audible and/or tactile feedback to the user.

FIG. 10 schematically shows an oblique sectional view of a secondembodiment of a drive mechanism. This drive mechanism essentiallycorresponds to the one described in conjunction with FIGS. 2. to 9. Incontrast thereto, the stop member 26 is secured against rotationalmovement and displacement with respect to the housing (13, 17, 40). Stopmember 26 may be integrated in housing part 40 or 17 or an insertthereof. Housing part 40 may be housing 13, for example, Housing part 17may be inserted and fixed within housing 13. Fixing elements 64 mayengage corresponding elements in the housing for fixing the housing part17 to housing part 40.

In order to compensate for the relative axial displacement betweenrotation member 21, drive member 20 and stop member 26, when therespective parts rotate with respect to one another, the rotation member21 is movable with respect to the housing. In order to keep stop member26 and rotation member 21 in, preferably permanent, abutment with drivemember 20 during medication delivery operation of the drive mechanism,resilient member 31 exerts a force on the rotation member 21, preferablyon protruding member 33 thereof which presses rotation member and drivemember 20 towards stop member 26. Resilient member 31 may be arranged atthat side of the drive member which faces away from the stop member,e.g. its proximal side. Resilient member may abut the proximal face ofprotruding member 33. Support member 32 can thus be dispensed with. Thedistal end face of housing part 17 may act as an abutment surface forthe resilient member 31.

However, when the elements are arranged as shown in FIG. 10, axialmovement of the rotation member, which may occur correspondingly to theaxial movement of the stop member in the previous embodiment, may betransferred to the dose part 16 and thereby to the user. This movementof an external part might be irritating for a user.

FIGS. 11 to 15 schematically show a third embodiment of a drivemechanism which is suitable for being provided in the medicationdelivery device 1 as described in conjunction with FIG. 1.

The drive mechanism essentially corresponds to the one described inconnection with the previous embodiments. In contrast thereto, the drivemember 20 and, in particular, the rotation member 21 are rotatablearound a rotation axis which runs obliquely with respect to the axisalong which the piston rod 12 is displaced (displacement axis). Therotation axis (cf. axis A in FIG. 14) may run transversally, inparticular perpendicularly, with respect to the displacement axis and,in particular, with respect to a main direction of extent of the pistonrod 12.

Drive member 20 and rotation member 21 may be retained by an axis member50, which may extend through rotation member 21 and drive member 20.Axis A may run along axis member 50. Axis member may secure drive memberand rotation member against displacement with respect to the housing.Stop member 26 may be integrated into housing 13. Of course, stop member26 may also be embodied as a separate element. Axis member 50 may extendthrough stop member 26.

Drive member 20 comprises an outer toothing 51. Teeth of the outertoothing 51 may extend radially away from rotation axis A. Drive membermay be a toothed gear sleeve. The piston rod 12 is expediently providedwith an outer toothing 52. The outer toothing 52 of piston rod 12 andthe outer toothing 51 of the drive member 20 are arranged to engage oneanother. The outer toothing 52 of piston rod 12 and the outer toothing51 of the drive member 20 may be permanently engaged. When the drivemember 20 and the rotation member 21 rotate together in the seconddirection with respect to the housing 13, the piston rod 12 is alsodisplaced in the distal direction with respect to the housing. Thepiston rod does not rotate while it is displaced in the distal directionwith respect to the housing.

The piston rod 12 may be supported against deviation in the radialdirection with respect to the displacement axis, for example by means ofhousing part 17 through an opening 53 in which the piston rod mayextend.

In contrast to the previously described embodiments, the dose member 34and the rotation member 21 are not threadedly engaged. Rather, rotationmember 21 and dose member 34 are connected/coupled to one another via alever mechanism. The lever mechanism is adapted to convert movement ofthe dose member 34 with respect to the housing in the proximal directioninto rotational movement of the rotation member in the first directionwith respect to the housing and movement of the dose member 34 withrespect to the housing in the distal direction into rotational movementof the rotation member in the second direction with respect to thehousing.

Drive member 20 is prevented to rotate during setting of the dose onaccount of the stop member 26 preventing rotational movement of thedrive member in the first direction.

The lever mechanism may comprise a lever 55. Lever 55 is preferablysecured against rotational movement with respect to rotation member 21and preferably against (simultaneous) translational movement withrespect to rotation member 21. Preferably, lever 55 is formed unitarywith rotation member 21. Lever 55 is pivotally around the rotation axisin the first direction during dose setting and in the second directionduring dose delivery.

Dose member 34 may, preferably at its distal end, comprise an engagementmember 54, e.g, a pin, for engagement with the lever 55. Engagementmember 54 may engage the lever 55, in particular an opening 56,preferably an elongate opening 56 within lever 55.

Stop member 26 prevents rotational movement of the drive member in thefirst direction during dose setting as described previously.

FIG. 16 shows a schematic sectional view of a part of a resettable drivemechanism according to an embodiment in a delivery state. FIG. 17 showsthe resettable drive mechanism of FIG. 16 in a reset state.

The drive mechanism may correspond to the one described in conjunctionwith FIGS. 2 to 9. However, a reset mechanism for a drive mechanism asit is described in more detail below may also be provided for in theremaining drive mechanisms as described above.

The drive mechanism described in conjunction with FIGS. 15 and 16 is aresettable drive mechanism. For this purpose, the drive mechanismcomprises a reset mechanism. The reset mechanism may be switched betweena reset position and a delivery position.

In contrast to the drive mechanism described in conjunction with theprevious figures, the rotation member 21 is not shown in FIGS. 16 and17. However, a rotation member may nevertheless be provided. FIGS. 16and 17 only show a half of a section through the drive mechanism. Theadditional cut was made along piston rod 12.

As shown in FIG. 16, in the delivery state, drive member 20 and stopmember 26 are engaged with one another such that rotational movement ofthe drive member 20 with respect to housing 13 in the first direction isprevented and rotation of the drive member 20 in the second direction,opposite to the first direction, is allowed. Toothings 27 and 28 may beprovided for this purpose as described further above. Resilient member31 exerts a force acting in axial direction on stop member 26, saidforce tending to keep the stop member and the drive member engaged.Resilient member 31 may be arranged to keep stop member in engagementand, in particular, in abutment with drive member 20 in the deliverystate. The (biased) resilient member 31 may be supported by and,preferably, bear against bearing member 57. Bearing member may besupport 48 of FIG. 6, for example. Bearing member 57 is expedientlysecured against rotational movement and displacement with respect tohousing 13.

Rotation of the drive member 20 in the second direction may cause thepiston rod 12 to be displaced in the distal direction with respect tohousing 13. The piston rod 13 may rotate and translate in the distaldirection with respect to the housing for dose delivery as described inconjunction with FIGS. 2 to 10. Alternatively, the piston rod may bemoved in the distal direction with pure translatory movement (notexplicitly shown, cf. a drive mechanism according to FIGS. 11 to 15).The drive member 20 may engage the piston rod 12. The drive member 20may be splined to the piston rod 12. Preferably, there is no relativerotational movement possible between piston rod 12 and drive member 20.Also, the drive member 20 preferably cannot be rotated in the firstdirection on account of the (permanent) interlocking of the drive member20 and the stop member 26 when the reset mechanism is in the deliverystate.

Thus, when the drive mechanism is in the delivery state, movement of thepiston rod 12 in the proximal direction with respect to housing 13 to astarting position is prevented, because the stop member 26 preventsrotation of the drive member 20 in the first direction and the drivemember has to be rotated in the first direction, if the piston rod 12was to be moved in the proximal direction with respect to the housing 13into the starting position.

However, after a cartridge 4 has been emptied, i.e. after a distal endposition of the piston 10 and, in particular, of the piston rod 12 hasbeen reached, the piston rod has to be moved in the proximal directionback into a proximal starting position in order to allow the drivemechanism to be reused. Expediently, the drive mechanism is configuredto be switchable from the delivery state to a reset state. In the resetstate, the piston rod 12 may be moved in the proximal direction withrespect to the housing, for example by a user screwing and/or pushingthe piston rod 12 in the proximal direction.

The drive mechanism comprises a clutch member 58. Clutch member 58 ismovable with respect to housing 13, preferably displaceable with respectto the housing, between a delivery position D and a reset position R.The clutch member 58 may be moved back and forth between the deliveryposition and the reset position. The reset position may be arranged inthe distal direction as seen from the delivery position.

The clutch member 58 may be a sleeve. Piston rod 12 may extend throughclutch member.

In the delivery position, drive member 20 and stop member 26 areengaged. In the reset position, drive member 20 and stop member 26 aredisengaged (cf. the encircled region 59 in FIG. 17). Thus, when theclutch member 58 is in the reset position, the drive member may berotated in the first direction with respect to the housing 13 withoutthe stop member 26 preventing the rotation. Consequently, the piston rod12 may be moved in the proximal direction, e.g. by rotation with respectto the housing and on account of a threaded engagement to the housing,due to the drive member 20 and the stop member 26 being disengaged.

The clutch member 58 may comprise a protrusion 61. Protrusion 61 mayprotrude radially and preferably inwardly from a base portion 66 of theclutch member 58. The base portion may extend in the axial direction.Protrusion 61 may be arranged to move the drive member 20 and the stopmember 26 out of engagement when the clutch member is moved towardsreset position R. Protrusion 61 may be provided at or near the proximalend of the clutch member 58. A distal end face of protrusion 61 ofclutch member 58 may be arranged to couple to and preferably to abut aproximal face of stop member 26.

The reset mechanism furthermore comprises a clutch resilient member 60,for example a clutch spring member, like a coil spring and/or acompression spring, for example.

The clutch member 58 may extend along drive member 20, stop member 26,resilient member 31, bearing member 57 and/or clutch resilient member60. The clutch member 58 may be rigid. The clutch member 58 may have aconstant length.

Clutch resilient member 60 may be biased when the clutch member 58 is inthe delivery position. Biased clutch resilient member may exert a forceon the clutch member that tends to move the clutch member in the resetposition. Clutch resilient member 60 may bear on bearing member 57, inparticular on a distal face thereof.

Clutch member 58 may comprise a (additional) protrusion 62. Protrusion62 may protrude radially and preferably inwardly from the base portion66 of the clutch member 58. Protrusion 62 may be arranged in the regionof the distal end of the clutch member 58. Protrusion 62 may be arrangedto be abuttable by and is preferably abutted by clutch resilient member60. Clutch resilient member 60 may be supported by and, in particular,bear on a proximal face of protrusion 62.

The clutch resilient member 60 is arranged to exert a force on theclutch member 58 which force tends to move the clutch member 58 in thereset position R. When the drive mechanism is in the delivery state,this force is counteracted by a clutch stop member 63. Accordingly, inthe delivery state, clutch member 58 may be held in the deliveryposition by the clutch stop member 63.

In the delivery state, clutch stop member 63 is preferably securedagainst displacement with respect to the housing 13. Clutch stop member63 may be arranged to abut clutch member 58. A proximal end face of theclutch stop member 63 may abut a distal end face of the clutch member 58in the delivery state.

For resetting the device, the clutch stop member 63 may be moved, forexample removed, so as to allow the clutch member to move into the resetposition. Thereupon, biased clutch resilient member 60 which exerts theforce, which is no longer compensated by clutch stop member, on clutchmember 58. The force automatically tends to move clutch member 58 in thereset position R. The clutch member 58 may abut stop member 26. Stopmember 26 may tend to follow movement of the clutch member towards thereset position R.

In order to get into reset position the force exerted by e resilientmember 31 on the stop member 26, which force tends to hold drive member20 and stop member 26 in engagement, has to be overcome. Thus, the forcemoving the clutch member 58 towards the reset position 58 has to begreater than the force exerted by the resilient member 31. The force formoving and, in particular, holding the clutch member 58 in resetposition R may be provided for by clutch resilient member 60. It isexpedient for the resilient member 31 and the clutch resilient member 60to be embodied as a spring member, respectively. Clutch resilient member60, in this case, preferably has a spring strength greater than the oneof resilient member 31 in order to overcome the force exerted byresilient member 31.

The clutch stop member 63 is expediently formed in the cartridge unit,for example, by the cartridge 4 or the cartridge retaining member 11.Thus, if the cartridge unit is detached from the housing 13 forreplacing an empty cartridge, the clutch member 58 is moved, preferablyautomatically, towards and into the reset position and preferably heldin the reset position.

The distance by which the clutch member 58 moves with respect to thehousing 13 when moving from delivery position into reset position ispreferably chosen to be great enough to disengage toothings 27 and 28.

The clutch member 58 is expediently secured to the drive mechanism inorder to avoid the clutch member falling out of the housing. For thispurpose, the clutch member may abut a proximal face of the stop member26.

As shown in FIG. 17, when the clutch member 58 is in reset position R,the drive mechanism is in the reset state and the piston rod 12 may bemoved in the proximal direction with respect to the housing from adistal end position back into a proximal starting position. When a newcartridge 4 is attached to the housing 13, after the piston rod 12 wasmoved back into starting position, clutch member 58 may be moved intothe distal direction back into delivery position together with thecartridge 4 and, if present, the cartridge retaining member 11, therebymoving drive member 20 and stop member 26 again into engagement.

Accordingly, the medication delivery device may be reused. As an elementof the cartridge unit like cartridge 4 or cartridge retaining member 11may serve as the clutch stop member 63, the reset mechanism mayautomatically and, in particular (purely) mechanically, decouple stopmember 26 and drive member 20, when the cartridge unit 2 is detachedfrom the drive unit 3 (cf. FIG. 1). Thus, the only action required by auser is to move, e.g. screw and/or push, the piston rod 12 back into thestarting position before a new cartridge unit 2 may be attached to thedrive unit 3. The drive mechanism is thus easily reusable.

The reset mechanism described herein above may be implemented easily andrequires only a small amount of additional parts such as compared to thecorresponding non-resettable drive mechanism. In particular, such ascompared to the first embodiment, only two additional parts—clutchmember and clutch resilient member—are required for the automatic resetmechanism.

As the reset mechanism may be an automatic one, no external action isrequired for disengaging stop member and drive member. Thus, the clutchmember may be retained in the housing and, in particular, inaccessiblefrom the outside.

Of course, the reset mechanism may be implemented as a manual,non-automatic mechanism. It is expedient, in this case, to configure themovement of the clutch member to be externally actuable.

In contrast to the situation depicted in FIGS. 16 and 17, the clutchmember 58 may be (partly) arranged outside of the housing. The housingmay be provided with one or more openings through which the clutchmember may extend from the outside to the inside of the housing. This isparticularly expedient for a non-automatic reset mechanism.

With the (resettable) drive mechanisms described herein above a gooddose accuracy may be achieved. The drive mechanisms are particularlysuitable for dispensing doses of the medication from and including 1 IUup to and including 30 IU, preferably from and including 3 IU up to andincluding 20 IU. Also, doses of 30 IU or more or 1 IU or less may bedispensed by means of the described drive mechanisms. However, doses offrom and including 1 IU up to and including 30 IU are particularlysuitable. For example, if a device described in conjunction with FIGS. 1to 10, in which the piston rod rotates during displacement, was to bedesigned for doses less than 1 IU, the thread of the piston rod shouldhave a low pitch and/or the number of teeth of the respective toothingof drive member and rotation member should be increased. Of course, theproduction costs may increase on account of the finer segmentation ofthe toothings and the lower pitch thread. In order to provide for adevice configured to deliver doses greater than 30 IU, e.g. 50 IU orgreater, the thread in the piston rod should have a higher pitch.Consequently, small deviations from a predetermined course of the threadresult in major absolute deviations from the desired dose. Thus, therisk of a reduction in dose accuracy may be increased. In addition, therisk of self-locking of a threaded engagement may be increased.

A diameter of the (outer) housing of the medication delivery device maybe less than or equal to 20 mm, preferably less than or equal to 16 mm,particularly preferably less than or equal to 14 mm.

A first aspect of the invention provides a drive mechanism for apredication delivery device (1), comprising:

a housing (13, 17, 40) having a proximal end and a distal end,

a rotation member (21) which is adapted to be rotated in a firstdirection with respect to the housing during setting of a dose of amedication (5) and to be rotated in a second direction with respect tothe housing during delivery of the dose, the second direction beingopposite to the first direction,

a piston rod (12) which is adapted to be displaced in a distal directionwith respect to the housing for delivering the dose,

a drive member (20) which follows rotational movement of the rotationmember in the second direction during delivery of the dose, and

a stop member (26) which prevents rotational movement of the drivemember with respect to the housing in the first direction during settingof the dose, wherein the rotational movement of the drive member in thesecond direction is converted into movement of the piston rod in thedistal direction with respect to the housing.

A second aspect provides a drive mechanism according to the firstaspect, wherein the drive mechanism comprises a dose member (16, 34, 41)which is moveable with respect to the housing (13, 17, 40) duringsetting and delivery of the dose, and wherein movement of the dosemember with respect to the housing is converted into rotational movementof the rotation member with respect to the housing.

A third aspect provides a drive mechanism according to the secondaspect, wherein the dose member (16, 34, 41) is secured againstrotational movement with respect to the housing (13, 17, 40).

A fourth aspect provides a drive mechanism according to any one of thefirst through third aspects, wherein the drive member (20) and therotation member (21) are rotatable about a common rotation axis.

A fifth aspect provides a drive mechanism according to the fourthaspect, wherein the piston rod (12) is displaced in the distal directionwith respect to the housing (13, 17, 40) along the rotation axis.

A sixth aspect provides a drive mechanism according to the fourthaspect, wherein the piston rod (12) is displaced in the distal directionwith respect to the housing (13, 17, 40) transversally with respect tothe rotation axis.

A seventh aspect provides a drive mechanism according to any one of thesecond through sixth aspects, wherein the dose member (16, 34, 41) andthe rotation member (21) are threadedly engaged.

An eighth aspect provides a drive mechanism according to any of thesecond through sixth aspects, wherein the dose member (16, 34, 41) andthe rotation member (21) are coupled to one another by a lever (55), thelever being pivotally around the rotation axis during movement of thedose member for setting and delivery of the dose.

A ninth aspect provides a drive mechanism according to any one of thefirst through eighth aspects, wherein the drive member (20) abuts stopmember (26) and rotation member (21) during movement of the rotationmember for setting and delivery of the dose.

A tenth aspect provides a drive mechanism according to any one of thefirst through ninth aspects, wherein the rotation member (21) and thestop member (26) are held in abutment with the drive member (20) by aforce provided by a spring member (31) during setting and delivery ofthe dose.

An eleventh aspect provides a drive mechanism according to any one ofthe first through tenth aspects, wherein the drive member (20) and therotation member (21) are coupled to one another by a firstuni-directional friction clutch mechanism, which is configured to permitrelative rotational movement between rotation member and drive memberduring rotation of the rotation member in the first direction forsetting of the dose and to prevent relative rotational movement ofrotation member and drive member during rotation of the rotation memberin the second direction for delivery of the dose.

A twelfth aspect provides a drive mechanism according to any one of thefirst through eleventh aspects, wherein the drive member (20) and thestop member (26) are coupled to one another by a second uni-directionalfriction clutch mechanism, which is configured to prevent relativerotational movement between stop member and drive member during rotationof the rotation member (21) in the first direction for setting of thedose and to permit relative rotational movement of stop member and drivemember during rotation of the rotation member in the second. directionfor delivery of the dose.

A thirteenth aspect provides a drive mechanism according to any one ofthe first through twelfth aspects, wherein the stop member (26) issecured against rotational movement with respect to the housing (13, 17,40).

A fourteenth aspect provides a drive mechanism according to any one ofthe first through thirteenth aspects, wherein the stop member (26) ismoveable in an axial direction with respect to the housing (13, 17, 40).

A fifteenth aspect provides a medication delivery device (1) comprisingthe drive mechanism according to any one of the first through fourteenthaspects, and a cartridge (4), the cartridge holding a plurality of dosesof the medication (5).

Of course, the invention is not restricted by the embodiments describedabove.

The invention claimed is:
 1. A resettable drive mechanism for a medication delivery device, comprising: a housing with a proximal end and a distal end; a drive member rotatable in a second direction with respect to the housing for delivering a dose of a medication; a piston rod which is splined to the drive member, where rotation of the drive member in the second direction causes displacement of the piston rod in the distal direction with respect to the housing; a stop member adapted to prevent rotation of the drive member with respect to the housing in a first direction opposite to the second direction when the stop member engages the drive member; and a clutch member movable with respect to the housing between a delivery position and a reset position, wherein when the clutch member is in the delivery position, the stop member and the drive member are engaged and the drive member is prevented from rotating in the first direction with respect to the housing and when the clutch member is in the reset position, the drive member and the stop member are disengaged, the drive member is rotatable in the first direction with respect to the housing and the piston rod is movable in the proximal direction with respect to the housing.
 2. The resettable drive mechanism of claim 1, wherein the piston rod is threadedly engaged with the housing.
 3. The resettable drive mechanism of claim 1, wherein there is no relative rotation between the piston rod and the drive member.
 4. The resettable drive mechanism of claim 1, wherein the clutch member is rigid and has a constant length.
 5. The resettable drive mechanism of claim 1, wherein the clutch member is secured in the drive mechanism in order to prevent the clutch member from falling out of the housing.
 6. The resettable drive mechanism of claim 1, wherein a diameter of the housing is less than or equal to 20 mm.
 7. The resettable drive mechanism of claim 1 further comprising a dose member which is movable in the proximal direction with respect to the housing for setting the dose of medication and in the distal direction with respect to the housing for delivering the set dose, wherein movement of the dose member for delivering the set dose is converted into rotational movement of a rotation member with respect to the housing in the second direction.
 8. The resettable drive mechanism of claim 7, wherein the rotation member is operatively connected to the drive member to rotate the drive member in the second direction.
 9. A medication delivery device, comprising the resettable drive mechanism of claim 1, wherein the medication delivery device further comprises a clutch stop member, wherein the clutch stop member is secured to the housing when the clutch member is in the delivery position, and wherein the clutch stop member is removable from the housing in order to allow that the clutch member moves from the delivery position into the reset position. 